Re: [PATCH v2] usb: cdns3: Fix deadlock when using NCM gadget

[Sebastian Andrzej Siewior]

On 2025-03-18 11:09:32 [-0400], Ralph Siemsen wrote:
> The cdns3 driver has the same NCM deadlock as fixed in cdnsp by commit
> 58f2fcb3a845 ("usb: cdnsp: Fix deadlock issue during using NCM gadget").
> 
> Under PREEMPT_RT the deadlock can be readily triggered by heavy network
> traffic, for example using "iperf --bidir" over NCM ethernet link.
> 
> The deadlock occurs because the threaded interrupt handler gets
> preempted by a softirq, but both are protected by the same spinlock.
> Prevent deadlock by disabling softirq during threaded irq handler.
> 
> cc: stable@xxxxxxxxxxxxxxx
> Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
> Signed-off-by: Ralph Siemsen <ralph.siemsen@xxxxxxxxxx>

Reviewed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

Sebastian